Circuits for measuring or calculating electrical signals such as current, voltage, and power and circuits for measuring or calculating electrical parameters such as impedance, admittance, phase relationships are used in a variety of applications including impedance measurements, load detection and calibration, security systems, smart grids, sensor interfaces, automotive systems, self-test systems, etc. For example, circuits used for determining the impedance of a system may include a resistor placed in series with a load so that the current flowing through the resistor can be used to determine the current flowing through the load. Drawbacks with this technique are the reduction of the input voltage range, the consumption of large areas of semiconductor material to manufacture the circuits, frequency limitations of the circuit elements, and the need for highly accurate circuit elements.
In some applications it may be desirable to detect a ground fault condition. One technique for detecting this condition is to establish resonance in an inductor-resistor-capacitor network when it is exposed to a ground-to-neutral condition. Resonance may be established by delivering a pulse to a positive feedback system that includes an operational amplifier. Alternatively, a steady state stimulus can be delivered to the circuit, which is then monitored for significant changes in the waveform profile. Drawbacks with these techniques are that they are prone to temperature and manufacturing shifts which reduce the accuracy of detection.
Accordingly, it would be advantageous to have a circuit and method for determining electrical signals and electrical parameters of a circuit element. It would be of further advantage for the circuit and method to be cost efficient to implement.